压花锚锚固性能的试验研究与数值分析  

EXPERIMENTAL STUDY AND NUMERICAL ANALYSIS OF ANCHORAGE PERFORMANCE OF BULB ANCHOR CABLE

作　　者：张永兴[1] 饶枭宇[1] 唐树名[2] 罗斌[2] 李剑[1] 

机构地区：[1]重庆大学土木工程学院,重庆400045 [2]重庆交通科研设计院,重庆400067

出　　处：《岩石力学与工程学报》2008年第3期607-614,共8页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家杰出青年科学基金项目(50625824);交通部西部建设科技项目(200431874010)

摘　　要：普通预应力锚索在我国已有数十年的应用,其常见破坏模式是锚索与注浆体的脱黏。为防止该类破坏模式的发生并增强内锚固段的锚固能力及锚固系统的安全可靠度,将结构工程中的压花锚引入到岩土锚固工程中并进行较大改进。设计6种不同配合比的注浆体,将普通锚、压花锚锚固在硬岩中,通过抗拔试验获得岩锚的荷载–位移全过程曲线。研究结果表明:压花锚阻止了钢绞线的轴向解扭,大大增强锚索承载能力,提高锚筋材料的利用效率,降低锚索承载力对注浆材料的敏感性,改变普通预应力锚索的失效破坏模式。利用ANSYS建立岩锚抗拔试验的有限元计算模型,研究内锚固段的受力特点,分析结果表明:压花锚在注浆体里产生楔形效应,形成注浆体剪切强度和抗压强度的联合作用,改变普通锚的力学作用机制,是造成上述试验结果的根本原因。鉴于压花锚的优良锚固性能和经济实用性,建议在岩土锚固工程中推广应用。The conventional prestressed anchor cable has been widely used for decade in China; and the dominant failure model is the debonding at the cable-grout interface. In order to avoid debonding, the bulb anchor cable in structural engineering is modified appropriately and used in geotechnical engineering to enhance the anchorage capacity of embedment section and the reliability of anchorage system. Six cement-based grouts with different mixing ratios are designed, in which conventional and bulb anchor cables are embedded in hard rock. Then the complete load-displacement curves of the rock anchors have been obtained by pull-out tests in laboratory. The test results indicate that the bulb anchor cables can prevent axial untwisting of anchor cables, greatly increase ultimate capacity of anchor cables, enhance utility efficiency of cable materials, reduce sensibility of the load capacity of anchor cables to the grout materials, and change the failure model of the conventional prestressed anchor cables; the possible failure model of bulb anchor cable is tendon fracture. Through establishing finite element calculation model for pull-out test of rock anchors with ANSYS, the stress distribution of embedment section is studied. Numerical analyses demonstrate that the bulb anchor cables change the mechanical action mechanism due to wedging effect that is a combination of the shear and compressive strength of the grouting material, which is the fundamental cause for the above test results. For the excellent anchorage performance and economical practicability of bulb anchor, it is worthy to be applied popularly to geotechnical anchorage engineering.

关 键 词：岩石力学 压花锚 普通锚索 锚固性能 解扭 楔形效应 

分 类 号：TU45[建筑科学—岩土工程]